In this June 8, 1972, file photo taken by Huynh Cong “Nick” Ut, South Vietnamese forces follow behind terrified children, including 9-year-old Kim Phuc, center, as they run down Route 1 near Trang Bang after an aerial napalm attack. (AP Photo/Nick Ut)

TRANG BANG, Vietnam — He stands in the northbound lane of Vietnam's Highway 1, traffic swirling around him, horns honking. He is pointing. Right there, he says — that's where it happened. That's where the screaming children appeared. That's where I made the picture that the world couldn't forget.

Huynh Cong "Nick" Ut was 21 on that day more than half a lifetime ago when he stood on the same road, pointed his camera northeast and captured one of history's most famous images — a naked Vietnamese girl screaming and fleeing after South Vietnamese planes looking for Viet Cong insurgents attacked with napalm from the air.

On Monday, 43 years later to the day, Ut went back to document some of his Vietnam War memories with a tool from an entirely different era — a 4-ounce iPhone 5 equipped with the ability to send photos to the world in the blink of a digital eye.

"I stood here and watched the bombs come down," Ut said of those long-ago moments just before he exposed a frame of Kodak Tri-X black-and-white film that carried the likeness of 9-year-old Kim Phuc, her body severely burned.

"I was so young then," the longtime Associated Press photographer said.

Ut's June 8, 1972, image of Kim Phuc, now known as the "napalm girl," helped crystallize the debate America had been having for more than half a decade about a far-off war that was lethal to so many. But the image began its persuasive work on newspaper pages many hours later, not in the instantaneous fashion we see today.

So when Ut returned to the village of Trang Bang on Monday, he came equipped with something more era-appropriate: He brought his iPhone with him and was given custody of AP Images' Instagram account for the day.

That gave him the power to upload, instantaneously, images that during the war would have taken hours to get 25 miles south to AP offices in Saigon, then in and out of the film-developing process before a print could be beamed to the world.

Sitting in a van bound for Trang Bang, Ut, a digital Leica around his neck, took a few practice shots with the iPhone. As he headed north from Ho Chi Minh City, formerly Saigon, the scenery revealed the ways Highway 1 has changed since the war. Today's roadside attractions include a restaurant called "Sushi World" and a roadside vendor hawking a small-scale Statue of Liberty.

Then, as the van crossed a bridge, he announced arrival at the site of the famous image: "Right here! Right here!"

He pressed the phone against the windshield to photograph the road, then followed up with an image of the temple where Kim Phuc and her family took refuge before the bombing.

Ut has made this journey often — usually at least once a year in recent years, he says. It remains significant to him. He and the picture — and, by extension, the village — are forever linked.

In Trang Bang, Ut visited a roadside stall operated by two of Kim Phuc's cousins, then walked a kilometer down the road to where he made the famous image. There, he faced a gaggle of photographers as traffic changed lanes to avoid them.

The scene that unfolded was a curious one: Ut taking pictures, Ut taking pictures of his own pictures, people taking pictures of Ut taking pictures. By the time it wrapped up, it was unclear whether more images were taken by Nick Ut or of him.

Ut ended up posting six images of Trang Bang on Instagram, including one of Ho Van Bon, 54, Kim Phuc's cousin and the boy to her left in the 1972 photo. Today, sitting at the roadside stall, he says instantaneous photo sharing can be a potent force when bad things happen.

"If this were to happen right now ... it's much better for the world now for these social networks to have instant attention for something," he said through a translator. "It makes the world a better place."

It wouldn't just be Ut uploading, though. His photo, as powerful as it is, would have had competition for the eyeballs of the world.

"Imagine what it would have been like in 1972 if you had all the technology and systems of 2015," says David Campbell, a visual storytelling expert and teacher in Newcastle, England.

"Some of those people escaping that napalm attack would have had their own smartphones. Some of the soldiers would have had smartphones," Campbell says. "In 1972, you got to see a very curated, edited selection of images that were much more isolated pieces of time. Now you would see greater scope, greater time scale and a much more comprehensive view."

Ut, whose AP photographer brother Huynh Thanh My was killed in the Vietnam War in 1965, suspects the conflict would have played very differently for people back in the United States — and their policymakers — if instantaneous photo sharing had existed then. He says that before he even got his film back to Saigon, "it would have been on Facebook."

"My God. Today in Vietnam everybody has a phone," Ut says. "A couple hours, that was too long. Now two minutes you get it to the world. I couldn't have imagined."